Science at ALCF

Three-dimensional reactive Navier-Stokes direct numerical simulation of a flame acceleration in a rectangular 81 cm long tube with a 2.54cm x3.81 cm cross-section filled with a stoichiometric 2H2 + O2 mixture initially at atmospheric pressure. The flame was ignited at the end wall with an electric spark discharge with 0.01 J of energy. Location of the spark is shown as a red dot on the top frame. The frames show density field in a two-dimensional X-Z crossection of the tube passing through the centerline of the tube. Density scale is shown on the middle frame. F - flame, PW - pressure waves generated by the accelerating flame. S - leading shock wave formed ahead of the flame at later times. The bottom frame is shifted horizontally by 15 cm relative to the top and middle frames. Physical model includes multi-species equation of state, viscosity, diffusion, and 8 species chemical kinetics scheme. Numerical resolution is 12 microns. Simulations were performed using a high-speed combustion and detonation code (HSCD) developed using 2011-2013 INCITE and ESP allocations on Intrepid and Mira. A. Khokhlov (U Chicago), J. Austin and A. Knisely (Univ. of Illinois at Urbana-Champaign), M. Garcia (ANL)

First-Principles Simulations of High-Speed Combustion and Detonation

PI Name:

Alexei Khokhlov

PI Email:

ajk@oddjob.uchicago.edu

Institution:

The University of Chicago

Allocation Program:

INCITE

Allocation Hours at ALCF:

150 Million

Year:

2015

Research Domain:

Chemistry

This research seeks to understand the mechanisms responsible for deflagration-to-detonation transition (DDT) to help determine safety measures in settings as varied as industrial sites and nuclear production facilities. Because detonation occurs quickly and on a very small spatial scale compared to the size of the system, high-resolution, multidimensional simulations are the most feasible method by which to investigate the detailed physics of a DDT.

This study requires first-principles, compressible, reactive flow Navier-Stokes direct numerical simulations, which take into account and explicitly resolve physical processes on spatial scales ranging from meters to microns, as well as attendant shocks, discontinuities, and physical variables.

Initial studies will focus on hydrogen-oxygen mixtures, which have relatively simple chemical kinetics. The research will then extend to hydrogen-air; syngas, a synthetic mixture of H2 and CO used as a clean fuel for increasing energy efficiency, and; ethylene, among the most used hydrocarbons in chemical industries.

Where such simulations were not practical in the past, the supercomputing power of ALCF’s Mira will allow for the spatial and temporal resolutions necessary to accurately investigate such processes. Researchers will perform these simulations using a reactive flow Navier-Stokes high-speed combustion and simulation code. The code incorporates detailed physics and chemistry suitable for hydrogen combustion and high-resolution treatment of shock waves, and it supplies a uniform grid as well as static and dynamic adaptive mesh refinement capabilities.

By better understanding the complex mechanisms involved in these reactions, researchers and engineers will be able to better predict the onset of detonation and develop safety mechanisms for real-world applications.